1. Field of the Invention
The present invention relates to a projector that incorporates a mechanism for a component that is to be cooled by a coolant.
2. Description of the Related Art
Cooling the heat-generating parts within a projector is crucial for extending the life of constituent components and improving the reliability of the projector. In particular, the optical modulation element and cold mirror must be cooled to below a prescribed temperature. For this purpose, a method has been disclosed in Japanese Patent Laid-Open Publication No. 2004-77883 in which a heat sink having heat-radiation fins is directly attached to the optical modulation element and this heat sink is then air-cooled by means of an air-cooling fan. Japanese Patent Laid-Open Publication No. 2000-77585 discloses a configuration in which a Peltier element is interposed between optical elements and thin heat sink is then air-cooled by means of an air-cooling fan. The cold mirror is also air-cooled by arranging a heat sink on the rear surface to absorb infrared rays and then cooling this heat sink by means of an air-cooling fan. However, the demand for higher luminance in recent years has resulted in the use of lamps with higher power, and this has resulted in the generation of even more heat in the optical modulation element and cold mirror. This change has necessitated larger air-cooling fans for air-cooled designs, with the attendant disadvantage of increased noise. Alternatively, Japanese Patent Laid-Open Publication No. H11-282361 discloses an image display device in which cooling is realized by providing a circulator and then circulating a cooling medium through a cooling container that is formed as a single unit with a heat generator such as a reflector.
As described above, the necessity for a larger air-cooling fan when air-cooling is used in a high-luminance projector and the problem of the attendant increase in noise is a common problem. On the other hand, the cooling method that employs a cooling medium that is disclosed in Japanese Patent Laid-Open Publication No. H11-282361 does not disclose any countermeasures for the changes in the expansion in the volume of the cooling liquid that are caused by temperature changes along the circulation route.